Process for producing nylon tire cord

ABSTRACT

The flatspotting characteristics of nylon tire cord reinforced tires can be substantially minimized by including in the nylon tire cord the reaction product of boric acid and an aliphatic alcohol.

United States Patent Richard W. Kibler Cnyahoga Folk, Ohio Dec. 10, 1968Nov. 16, 1971 The Firestone Tire 8: Rubber Company Akron, OhioContinuation-impart of application Ser. No. 444,464, Mar. 31, 1965, nowPatent No. 3,459,251, dated Aug. 5, 1969. This application Dec. 10,1968, Ser. No. 783,466

Inventor Appl. No. Filed Patented Assignee PROCESS FOR PRODUCING NYLONTIRE CORD 1 Claim, 2 Drawing Figs.

US. Cl. 264/235 Int. Cl B29c 25/00 Fieldofsearch 264/232, 4-5, 340, 342,5,184;8/l30.1; 117/7, 138.8 N;

260/78 L, 78 S, 78 SC References Cited UNITED STATES PATENTS 6/1951Walker 260/78 SC 8/1962 Pamm 1 17/7 8/ 1964 Flnestone et a1 260/787/1965 Ahles et a1. 264/234 4/1966 Coats, Jr l17/138.8N 10/1966 Skeeneta1.. 117/7 6/1967 Bonner, Jr 8/ 1 30.1

FORElGN PATENTS 0/1941 Great Britain 260/78 SC Primary EXaminer-RobertF. White Assistant Examiner-G. Auville Attorneys-S. M. Clark and WillardL. G. Pollard ABSTRACT: The flatspotting characteristics of nylon tirecord reinforced tires can be substantially minimized by including in thenylon tire cord the reaction product of boric acid and an aliphaticalcohol.

PATENTEDNUV 16 nan 3,621,090

PROCESS FOR PRODUCING NYLON TIRE CORD This application is a division ofmy application Ser. No. 444,464 filed Mar. 3 l, 1965, now US. Pat. No.3,459,25 I.

This invention relates to nylon tire cord, yarns and filaments for usein nylon tire cord, nylon cord tires, and to an improvement in theprocess for producing nylon tire cord.

A number of different nylon compositions have been used in theproduction of tire cord. The use of nylon tire cord has, however, beenlimited as a result of a phenomenon commonly referred to asflat-spotting. When a vehicle stands for an extended period of time,those portions of the tires which are in contact with the groundflatten. The flattened portion tends to be retained for a substantialperiod of time afler the vehicle is placed in operation. As the tirerotates, there is a decided thumping or slapping sound resulting fromthe flat spot on the tire. With many tire cords, what little flat spotis formed runs out quickly. However, the properties of nylon tire cordare such that the flat-spotting is retained substantially longer thanwith tires utilizing other tire cord materials.

In general, the tendency of an ordinary tire cord to flatspotting, asreflected in its response lag" measurement described hereinbelow, is ofthe order of 200 to 250 mils. The usual approach to preventflat-spotting has been to increase the initial modulus (determined asdescribed hereinbelow) of the tire cord by altering the polyamide in thetire cord, e.g., by mixing with high-melting polyamides, cross-linking,grafting and/or block polymerization. In general, the modulus isincreased until the response lag is reduced to 160 mils or less.

This method has been reasonably successful in minimizing flat-spotting,but has not eliminated it. In fact, to the extent that any flat-spottingtendency remains after this treatment, the flat spot lasts for a muchlonger period of time before running out," i.e., the vehicle must beoperated for a considerably longer period time at any given speed tocause the disappearance of the flat spot.

It has now been found that the reaction product of boric acid and analiphatic alcohol can be added to nylon filament, yarn, or tire cord,referred to hereinafter as nylon structures, to provide a product havingimproved properties which tend to minimize the problems associated withflat-spotting. The reaction product may be added directly to the formedstructure or may be introduced into a nylon melt prior to the spinningor otherwise forming of the nylon structure.

It has also been found that while the introduction of the boricacid-alcohol reaction product into the nylon reduces the initial modulusof the nylon structure, the modulus at higher stresses is substantiallyunaffected. For example, at stress values of 6 to 8 pounds, thestress-strain curve for the treated material again becomes substantiallythe same as that for the untreated materials. The tensile properties ofthe treated material are not seriously reduced by the treatment. Allstress valves given herein are for a cord of 2x840 denier yarn unlessotherwise indicated. Equivalent value for material of different deniercan, of course, be determined in the usual manner.

Tire cord produced according to the present invention provides theadvantage that any flat-spotting will tend to run out in a very shortperiod after operation of a vehicle utilizing tires containing such tirecord. Further, because of the lower initial modulus and response lag,the flat spot is more yielding on the road, thus removing the amount ofobjectionable interaction between the wheel and the road. Thus, theundesirable thumping or slapping will be, at most, of very shortduration and of less objectionable character. Carried to the ultimate inthis direction, the flat spot will disappear during the first revolutionof the tire and no flat-spotting will be detected.

In accordance with the present invention, the boric acidaliphaticalcohol reaction products, which are useful, comprise those in which theboric acid has been reacted with an aliphatic alcohol having a boilingpoint substantially above l C. and wherein the reaction product is inliquid form under the conditions of use. As used herein, the reactionproduct is in liquid form under the conditions of use if it can bedissolved in a noninterfering solvent, e.g., an excess of the alcohol,or if it can be melted and/or heated to provide the desired fluidity foraddition to the nylon structure, either in filament form or as a melt,at a temperature which is noninjurious to either the reaction product orthe nylon structure.

It is not essential that the reaction between boric acid and the alcoholproceed to esterification. Thus, the reaction products useful in thepresent invention include complex compounds formed by mixing boric acidwith alcohol without the evolution of water. The resulting solution ofcomplex compound is useful without further treatment. It has been found,however, that a superior additive is obtained if at least part of thewater of reaction is removed to provide a product that is at leastpartially esten'fied. Thus, the present invention contemplates the useof the simple esters of boric acid including the mono-, di-, andtriesters of boric acid. In its most preferred form, however, theinvention contemplates the use of polyesters of boric acid, e.g., thepolymeric reaction product of boric acid and a polyhydric alcohol.

In the preferred form of the invention, the reaction product is anonvolatile ester of boric acid and a polyhydric alcohol. Bynonvolatile" is meant that the ester will char before distilling evenwhen under reduced pressure. These products are formed generally byremoving the water of reaction from the reaction mixture.

Among the monohydric alcohols which are useful herein are the higherboiling alcohols, e.g., n-butyl alcohol and isobutyl alcohol, the amylalcohols, hexyl alcohols, heptyl alcohols, octyl alcohols, etc. Thehigher molecular weight aliphatic alcohols, such as hexadecyl alcoholand octadecyl alcohol may also be employed and the alcohols may beeither straight chain or branched. The only limitations are thosedescribed previously, particularly as to the nature of the reactionproduct obtained.

Similarly, useful polyhydroxy alcohols include ethylene glycol,glycerine, trimethylene glycol, tetramethylene glycol, pentamethyleneglycol, etc., as well as the polyalkylene glycols such as diethyleneglycol, triethylene glycol, etc. It should also be recognized that thealcohols may be substituted with other groups provided those groups donot interfere with the formation of the desired reaction product, e.g.,boric acidalcohol complex, boric acid-alcohol ester, etc., and do notexert a deleterious influence on the nylon structure into which it is tobe incorporated. Examples of substituted alcohols areN-bem-hydroxyethylaniline, diethanolamine, triethanolamine, N,N-(bis-hydroxymethyl-alpha)-picoline, and the like.

The proportions of reactants are not critical in the production of theuseful reaction products provided, however, there is sufficient alcoholto provide at least one hydroxyl group per molecule of boric acid. Thus,for monohydric alcohols, there should be a mole ratio of alcohol toboric acid of at least l.0; for dihydric alcohols of at least 0.5; fortrihydric alcohols at least 0.33; etc. Substantial excesses of alcoholmay be employed. 'Ihus, useful trihydric alcohol-boric acid reactionproducts have been prepared from reaction mixtures in which the alcoholto acid mole ratio exceeded 3: l.

The most outstanding reaction product found useful in the presentinvention is that obtained by reacting glycerine with boric acid in amole ratio of l :l with the elimination of at least 2.5 moles of water.The resulting product is a polyester having particularly superiorproperties as an additive for nylon structures.

Other polyhydric alcohols may be employed in place of glycerine. ln thisrespect, the triols are particularly useful. However, any of thepolyhydric alcohols such as l,2,4-butanetriol; l,2,6-hexanetriol;glycerine dimer and polymers such as the commercial mixtures designatedas polyglycerol hydroxypropyl glycerine; Z-hydroxymethyl glycerine;trimethylolpropane; erythritol; arabitol; sorbitol; xylitol;pentaerythritol; or inositol, may be reacted with boric acid with theelimination of at least 2.5 mols of water to provide ester or polyesterreaction products which are useful in the present invention. Theglycerine boric acid polyester, however, is preferred as an exceptionaltreating agent for use in the present invention.

The present invention is particularly useful with Nylon-6. It is not,however, restricted to this nylon. Thus, the invention finds use withNylon-6, polycaprolactam; Nylon-66, polyhexamethlene adipamide; Nylon-7,polyenantholactam; Nylon-4, polybutyrolactam; and Nylon-5,polyvalerolactam, as well as with blends of various nylons, e.g., ablend of Nylon-6 and Nylon-61 (polylhexamethylene isophthalarnide).

The nylon to be treated may be in the form of yarn, filament, fiber, ortire cord. It is suitably treated by passing the specified nylonstructure through a bath of the treating agent. Thus the nylon structureis contacted with the treating agent. Thus the nylon structure iscontacted with the treating agent while the treating agent is in liquidform. This may be suitably accomplished by dissolving the boricacid-alcohol reaction products in a suitable solvent which will assistin attaining penetration of the reaction product into the nylonstructure. Where the reaction product is prepared from a reactionmixture having a molar excess of alcohol, the reaction product can beemployed as the treating bath without further dilution. Suitablesolvents for dissolving the reaction product, e.g., a polyester, toobtain a suitable bath include glycerine and N- betahydroxyethylaniline.Other polyhydroxy alcohols and aminohydroxy compounds which are capableof penetrating the nylon structure and which are capable of dissolvingthe reaction product find utilization in the present invention.

While the treating agent may be introduced into dipped tire cord, it ispreferred to treat cord prior to the final heat stabilization treatmentand cord dipping. Particularly advantageous results are obtained whenthe treating agent is introduced into the nylon structure subsequent tothe primary crystallization and orientation of the structure.

A number of factors must be considered to obtain a suitable product inaccordance with the present invention. It is necessary that thetreatment be conducted at an elevated temperature. While this will varydepending on the particular treating agent being employed, the minimumtreating temperature can be determined readily once the purpose andmanner of treating is understood. 1n some instances, a temperature ofthe order of 160 to 180 C. is most desirable; however, in many instancesthe reaction product solvent will not permit the use of suchtemperatures and lower temperatures on the order of 100 to 160 C. willbe necessary consistent with the properties of the solvent.

The duration of treatment is also quite important. While theeffectiveness of the treatment depends on a time-temperaturerelationship, it has generally been found that reducing the treatmenttime to less than about 9 seconds causes a drop off in the effectivenessof the present invention. Particularly good results are obtained withtreatments of at least seconds. Treatments in excess of seconds (and insome instances, in excess of a minute) may be necessary to produce acorresponding improvement in properties. The optimum time for anyparticular treating agent will vary, depending on the nature of thetreating agent, the particular nylon being treated and the temperatureof treatment. No additional benefit will be obtained by prolonging thetreatment beyond the optimum time for that particular set of materialsand temperature.

When treating tire cord, yarn and such nylon structures, good practicedictates that the structure be maintained under tension during the heattreatment. ln general, the yarn, cord or fibers are maintained under atension of 700-1,400 grams. As employed herein, tension is given as theforce exerted on a cord of 2x840 denier yarn Corresponding values formaterials of other denier are readily calculated in the usual manner.While under some circumstances lower or higher tensions can betolerated, under no circumstances should the tension drop below theminimum tension requirement for the treatment material which existsbetween 0 and 700 grams, e.g., 100 to 600 grams. The minimum tension isthat which is just sufficient to prevent substantial loss of fiberorientation under the conditions of treatment. Although the upper limitcan approach the breaking load, in general, it should be maintainedbelow about 2,500 grams. A tension in the range of about 600 to about800 grams is suitable.

The treatment is most satisfactorily effected by passing the nylonstructure through a bath of the treating agent maintained at the desiredtreating temperature. The tension of the nylon structure in the bath canbe maintained by standard tensioning means. The duration of thetreatment can be controlled by the location of the rolls in the treatingbath and the takeup speed of the nylon structure throughout the bath.

While the foregoing method is suitable, it is possible to pass the nylonstructure through a bath of treating agent at room temperature, and tothen pass the nylon structure for the desired treating time, eg, 2 to 3minutes, through a suitable oven maintained at the desired temperature,e.g., C. When treating a formed nylon structure, penetration of thetreating agent into the filament or fiber making up the yarns and/ortire cords is essential and this factor must be considered in selectinga suitable solvent for the reaction product.

lt is also important that the treating agent, once it has penetrated thestructure should be retained in the structure in an effective amountunder the conditions of temperature to which the treated tire cord willbe subjected in subsequent tire manufacturing operations. It appearslikely that the elfective amount of the treating agents enters into theamorphous portions of the drawn nylon filament without appreciablyaffecting the crystalline portions which give the nylon its desirabletensile properties. It is this which is one of the prime advantages ofutilizing the boric acid polyesters in the present invention. The borateesters are retained very efiectively in the nylon structure throughout anumber of processing operations. Thus, it is of little importancewhether the solvent be retained in the nylon structure provided thesolvent can provide the necessary penetrability for the reactionproduct. It has been found, however, that a number of these solvents arealso useful for lowering the response lag of the nylon structures. Ofthese, glycerine and anilinoethanol are particularly notable. Thus,retention of solvents such as those just mentioned, will further enhancethe properties of the treated product. A very substantial portion ofthese solvents will be lost, however, during the subsequent treatingoperations.

As will be noted in the examples, the preferred and superior treatingprocess for treating formed nylon structures in accordance with thepresent invention comprises passing the nylon structure under a tensionof 700 to 1,400 grams through a bath of the treating agent maintained ata temperature in the range of 100 to C. for a treating time of fromabout fifteen to about sixty seconds. By this method, nylon tire cordcan be obtained which is characterized by the presence of substantialquantities of the treating agent in the nylon structure and by aninitial modulus which is substantially less than the modulus of theuntreated nylon structure.

lt has been found to be advantageous to follow the treating process witha quick wash or other treatment to remove treating agent from thesurface of the nylon structure, followed by a supplemental heattreatment of the order of 3 minutes in duration in an air oven at atemperature of about 160 to C. 1n the examples which follow, allsupplemental heating was in an air oven unless otherwise stated.Unexpectedly, the washed and heated yarn, cord, or fibers have beenfound to have enhanced crystallinity, as indicated by X-ray data, overthat observed in like products wherein the same steps were followedexcept that the treatment with treating agent was omitted.

ln addition to treating the shaped nylon structure, it is also possibleto treat the nylon prior to the shaping operation. Thus nylon chipsprior to extrusion can be treated with a suitable treating solutionincorporating the boric acid reaction products which will be retained innylon structures formed from the nylon chips. As a general proposition,it has been found advantageous to use a volatile solvent for thereaction products when treating nylon chips or pellets prior to formingthe final nylon structure. A typical example of such a solvent ismethanol. Such solvents normally have extremely good penetrability ofthe nylon but very low retention in the nylon. Since the reactionproduct is the primary efi'ective treating agent, the loss of thesolvent is of little importance.

Still another efiective way of introducing the reaction products intothe nylon is at the melting stage. Suitably, nylon is melted andmaintained at an elevated temperature until a clear melt is obtained.Substantial quantities of boric acid lf the treatment given acordreduces both the response lag and the initial modulus sufficiently,a low flat-spotting efiect can be expected when the cord is used intires.

Details of the method for producing boric acid-aliphatic alreactionproducts may be introduced into this melt to form a 5 coho] reactionproducts will be found in the Journal of lhysihomogeneous solution whichcan be cooled and solidified Chemistry, VOL PP through whlle the withoutseparation of the reaction products. The resulting discussion there!"dll'ecled P p ly borates of product may then be treated in the samemanner that the p y y alcqholsy the melllods are apphcable to the reac'nylon would ordinarily be treated to form chips or nylon struc- Productsmonohydnc alcohols "Y?"- tures which are useful as tire cord. 10 in theexamples, the response lag and initial modulus were As was notedpreviously, there has been found to be a cordetermined 35 dlscussedabove relation between rate of recovery from flat-spotting of tirescontaining a particular tire cord and the response lag characteristicsof the nylon fiber or yarn which makes up the tire EXAMPLES A4 THROUGHcord. Response lag is determined by suspending a weight of 3 fi z ggi fzi g gj k fi l gz 53:: iii: gg i gi In accordance with the presentinvention, Nylon-6 greige so tested is l 660 to 2'000 At th 0 i t tirecord of 1,680 denier having a response lag of the order of e c n 0 a 240mils, was treated with a series of glycerine/boric acid 32 932 g iigiggf gj f t i gg gz g i g g reaction products produced by the reaction ofglycerine and p I d p d d d o an e boric acid with the elimination ofabout 3 mols of water. The 2 :3 :2 is Z fs fi z reaction product wasapplied as a solution in glycerine or in p a! a] d 1 1 o danilinoethanol or as the reaction product of a molar excess of :gginnvue 328 T: eijiignth o e ny on materil is measure glycerine with boricacid. ln all of the tests, treatment time was S a e f h h g one minute.The treating conditions and the physical propermen e g t a uilon o e rsties of the treated products are set forth in table A. In thetasuspensloln measurte g ml i; z t: bles the heading GI/BA. Molar Ratiorefers to the ratio of response ag. is importan 0 course, a e en re es I4 F n g ycerine to boric acid in the reaction product. 0 owing ga? ig tl tempterature g i treatment with the specified treating agent, thenylon cord was 5. 3 f es are a empera 0 an a re washed with water,alcohol, or a mixture of the two. The ala 0d 1 f d b0 cohol used inthese instances was ethanol; however, other e e ermmauon 0 mm u re em:to lower alkanols can also be used for the washing step. made on anlnstron Tester with flat, rubber-faced aws 10 As may be Seen from tableA the preferred and superior 9 g d f s g f i fl fz treating agent forthe purposes of the present invention coma SP6}: me es e amen prises a25 to 50 percent by weight solution in glycenne or c ampe in the aws,and the machine started on the S-poun anilinoethanol of theglycerine/boric acid polyester prepared scale. A tangent is drawn to theinked line on the chart atthe by the reaction of 1 mo] of glycerin and 1mo] of boric acid two percent elongat on location, and extended the fullwidth with the li i i f about 94 percent f the theoretical 3 of thechart. The initial modulus is calculated by the formula: 40 mols f watchwi h a l i a initial material pickup 227 0 0 of the order of 20 percentto 25 percent is attained with about I l 7 0 mtla modulus (g--)=denierxdifierence in elon; 10 percent retained atter the supplementalheat treatment. gation as determined by The response lag can be retainedsubstantially below 120 mils, the intercepts f th well below half thatof the untreated material, even after such tangent from 0 to 5- severeheat treatments as a combination of 15 minutes at 160 Pound load- C.followed by hours at C. in an air oven.

TABLE A Polyester treating agent Temp. 01'

- 1 min. Suppl. heat.

Polyester treat- H Percent Ro- Bn-uk lnit. lvrcont concenment 'Iimo Tommaterial spouse load, mod elongatratlont, 0.) Wash (111111.) (1.) pickuplag lbs. olden tion 138113811.

48 160 Water 3 160 10. 3 116 23. 5 15. 5 20. 0 48 160 15 150 8.92 10422.7 15.1 20.0 48 3 160 18.3 118 20. 4 11. 0 20. 1 48 15 160 14. 1 10530. 0 14.35 27.0 48 15 180 13.2 104 25.0 14.4 21.7 48 ....do 15 160 3.1119 23. 4 22.1 19.8

(Plus 63 hrs. at 92) 48 120 do 160 7.0 115 30.5 16.65 20.7

(Plus 63 hrs. at 92) 50 3 160 21.1 143 30.1 11.7 30. 0 50 15 160 11.5114 30. 2 12. 15 32.2 50 15 t 0 n30 4. 7 30.4 13 35 31. 3

. us 1 rs. a 9 A-11 1/1 Anl1lr1oethanoL... 42.6 3 160 19.4 116 29.0 10.230.5 A12 2/1 Untreated 150 do 3 100 20. 9 27.6 12.5 27.5 A13 15 14. 0117 27. 4 12.6 27. 0 1 .-14.. 15 100 8.0 123 20. 1 14. 2 26. 8 A-15. 315.7 110 24. 4 12.3 23. 5 A16 15 100 0. 4 117 27.7 12.3 28. 2 .4-17. 15160 3. 3 136 28. 8 14.35 28.3

(Plus 63 hrs. at 90) A-1s 3 160 25. 4 138 28. 7 12. 0 20. 6 A19 3 15025.4 138 28. 7 12.0 29. 6 A-20. 15 160 15.8 114 30. 1 12. 0 32. 0 A2l 15160 14. 4 114 30. 0 12.0 30. 3

(Plus 41 hrs. at 90) 1 .-22-. 3 160 25. 2 117 21. 0 11.4 21. n 1 .-23..15 160 14.2 115 28. 0 12.5 27.5 A-24. 6. 2 128 28. 1 13. 55 28.

15 160 (Plus 41 hrs. at 90) TABLE A Polyester treating agent Temp. 01 1min. Suppl. heat. Gl./B.A. Polyester treat- Percent Re- Break Init.Percent Run molar concenment Time Temp. material sponse load, mod,elonga- No. ratio Solvent tration, C.) Wash (mln.) C.) pickup lag lbs.g./den. tion percent A25. 1/1 Ani1lnoethanol 42. 5 117 do H 15 160 15.1114 A46" l/l -dO 42.5 15 160 9. 9 119 (Plus 63 hrs. at 92) A-27. 1/1Glycerine 50 3 160 29. 5 144 1 A28 1/1 ....do 50 15 160 29.5 116 A-29..1/1 d 50 15 160 19.9 112 (Plus 63 hrs. at 90) A30 l/1 .do 50 15 160 10.3131 (Plus 63 hrs. at 90) A-3i. l/1 Anllinoethanol. 42. 5 3 160 22. l 9927. 8 10. 29. 8 A-32. d 42. 5 3 160 20. 1 107 28. 4 9. 32. l A-33. 42. 53 160 20. 0 113 27. 9 9. 32. 0 11434.. 25 3 160 16.4 105 28.8 9. 7 31.0A-35 25 15 160 None 159 30. 1 17. 8 28. 7

(Plus 41 hrs. at 90) A-36. 25 3 160 15. 3 100 25. 6 9. 55 26. 7 A-37 253 160 13. 7 102 28. 7 8. 4 33. 9 A-38. 50 3 160 19.5 117 27. 2 11.1 26.0P 50 3 160 21. 9 108 27.0 11. 4 27. 6 A- 50 3 160 27. 5 130 28. 6 11.229. 3 A-41. 50 3 160 13. 8 122 29. 2 10. 32. 2 A42 48 3 160 24. 8 11729.6 9. 7 33. 8-

ethanol, 37% glycerine. A43 1/1 43 3 160 16. 2 116 28. 3 10.3 28. 11 48140 .do 3 160 20. 3 120 211. 4 10. 3 30.1: A-45. l 48 160 50% alcohol, 3160 23. 9 25. 5 10. 8 25.11

50% water.

A46.. 1 1 ....do 43 do 3 1 0 23.4 124 28.0 11.55 30.6 A47.. 1/1 .do 43do 3 1 0 25.2 125 28.5 9.8 3

EXAMPLES 8-] THROUGH 18-3 A 50 percent solution of glycerine/boratepolyester (l/l molar ratio with the elimination of 3 mols of water) wasmade by dissolving the polyester in an equal weight of methanol. Themethanol solution was poured over Nylon-6 chips and the mixture wastumbled. Methanol was then evaporated and the product was dried in anoven at 175 C. for 16 hours. Three different samples were prepared inthis manner to provide a product having respectively, two, four and sixparts by weight of polyester per 100 parts of nylon chips. The nylon wasthen passed through a standard screw extruder at 52 F. at the max- 40imum screw speed and the resulting extrusions were chopped to providefeed for a melt spinning unit. Yarns were drawn from the treatedmaterials with draw ratios of 5:1. Tire cords Nylon-6 was charged to aheating vessel and heated over a period of 35 minutes up to atemperature of about 260 C. at which temperature the nylon was a clearmelt. To this melt was added a glycerine/boric acid polyester reactionof 1 mol of glycerine with 1 mol of boric acid with the elimination of 3mols of water) to provide a melt containing 5 percent of the polyester.The melt was maintained at elevated temperature until the polyesterchange was completely dispersed in the melt. The solidified massretained the polyester and appeared to be a homogeneous blend.

in a second test the melt blending was repeated except that thepolyester content of the melt was increased to 10 percent. Thesolidified product again appeared to be a well-blended homogeneous mass.Following the usual procedures, the polymer mass was converted into yarnand the yarn converted into nylon tire cord of 1,680 denier. Thephysical properties of the tire cord were determined and are set forthin table C.

TABLE C '35 of Elonga- Run Polyester Tenacity. in 3. lion in ResponseNo. in Yarn per denier l Lag C-2 10% 3.ll I955: 62

EXAMPLES D-l THROUGH D-l9 The procedure of examples A-l through A-47 wasrepeated, except that the treating agent comprised complexes of boricacid with alcohols made by simply dissolving boric acid in the glycerineor other alcohol without drawing off any water. The treated nylon cordwas water washed in each in- (prepared by the 60 stance, but in someinstances, an acetone wash was also used.

The treating conditions and the physical properties of the treatedproducts are set forth in table D.

TABLE D Temp. 01 Suppl. heat.

1 min. Percent Break lnit. Percent treatment Time Temp material Responseload mod., elonga- Run No. Treating agent C.) Wash (min.) C.) pickup lag(lbs) g,/den. tlou D-1 25% boric acid, 75% glycarine 120 Water 15 14. 0101 '28 10.8 26. 0

3 160 21. 6 109 17. 9 9. 9 28. 7 3 160 25. 9 109 20. 9 13. 6 20. 5 15160 19.0 105 19.0 13.6 18. 7 3 160 13.9 134 D-6. .d0 15 160 9.1 D-7 50%boric acid, 50% glycerine 3 160 22. 7

complex. l)-8 d0 15 160 17. 8 D-9... 25% boric acid, 75% glycerine 15160 13.9

complex.

TABLE DContinued Temp. oi Suppl. heat.

1 min. Percent Break Init. Percent treatment Time Temp. materialResponse load mod., elonga- Run No. Treating agent 0.) Wash (min.) C.)pickup lag (ibs.) g./den. tion D- "am 120 -do 160 14.6 138 (plus 61 hrs.at 190 F.) D-ll t'lo 120 .do 3 160 16.3 151. D-12 25% boric acid, 75%anilino- 115 (1) acetone, 3 160 23.9 97 24. 4 7. 8 25. 3

ethanol. (2) Water. D-13 do 115 (1) water, 15 160 10. 1 128 27. 1 l4. 524. 8

(2) acetone. D-14 do 5 do 15 160 10.8 115 28.5 17.5 25.5

(plus 84 hrs. at 190 F.) D-15 31.21% btgrlc acid. 68.8% 130 do 15 16018. 8 118 24. 1 13. 1 21. 9

g oer ne. D-16.. 81. o boric acid, 68.8% 115 do 15 160 17.9 116anllinoethanol. D-17 dO 115 .do 15 160 8. 8 139 28. 7 20. 5 24- 0 (plus61 hrs. at 190 F.) D-18 ..d0 116 d 3 160 24.1 103 28.9 11.6 28.8 D-lQ.-d0 130 do 3 160 19. 9 113 27. 8 11. 8 27. 3

Half of boric acid reacted with NzOH.

EXAMPLES E-l THROUGH 15-10 20 EXAMPLE F The procedure of examples A-lthrough A-47 was repeated, except that the treating agent comprisedboric acid esters with anilinoethanol (the trivial name, usedhereinafter for brevity to designate N-beta-hydroxyethylaniline). Thetreated nylon cord was alcohol washed in each instance. The treatingconditions and the physical properties of the treated products are setforth in table E.

Nylon-6 tire cord was prepared from a blend of Nylon-6 I containing 5percent of glycerine boric acid polyester prepared from 1:1 mole ratioof glycerine and boric acid with elimination of about 3 moles of waterin accordance with the present invention. The yarn was 928 to 936 denierwith an elongation at break of 17.8 to 18.1 percent, a break load of13.2 to 14.0 pounds, and a response lag of 86 to 100 mils.

.f TABLE E Temp. oi Suppl. heat. 1m Percent Break lnlt. lcrceuttreatment Time Temp material Response load mod, elonga- Run No. Treatingagent C.) (min.) C pickup lag (lbs.) g./den. tion E-i 1 moleanilinoethanol, boric acid ester (1/1 115 15 160 24.7 127 31.3 18.2 28.?

mole ratio) dissolved in 1 mole anilineethanol. 15-?Aniiaiinoethanollboric acid ester (3/1 molar 115 3 160 18.8 144 re 0 E-3do 115 15 160 17. 7 150 E-4 1 mole anilinoethanol, borlc acid ester (3/1115 3 I 14.11 141 molar ratio) dissolved in 1 mole anilinoethanol. E-5do 115 15 180 i). 5 13-6 1 mole anilinoethanol, boric acid ester (3/1115 3 160 13.1

molar ratio) dissolved in 3 moles anilinoethanol. E-7 ..d0. 115 15 1608.0 E8. Anilinoethanol/borir acid ester, (3/1 molar 115 15 160 9.6ratio). (plus 41 hrs. at F) E-9 1 mole aniilnoethanol/boric acid ester(3/1 15 160 6.8 rrtiglar lratio) dissolved in 1 mole anillno- (plus 41hrs. at 190 F.) e ano E-10... 1 mole anilinoethanol/boric acid ester(3/1 15 3.1

mlollar ratio) dissolved in 3 moles anilino- (plus 41l1rs.at F.)

ano

flat-spotting. The tire tests bore out the showings of the r responselag tests that the products of the present invention did minimizeflat-spotting problems.

in the test employed on the tires, a tire mounted on an automobile isplaced in contact with a rotating drum. The drum, in turn, causes thetire to rotate. in this manner, the tire is caused to rotate for 15minutes at a rate corresponding to 80 miles per hour. The car is thenremoved from contact on the drum and allowed to sit for 17 hours. Thecar is then raised and the tire placed in contact with the rotating drumwhich caused the tire to rotate at a rate corresponding to 30 miles perhour. The presence of a flat spot on the tire will cause the wheel axleto undergo an acceleration, when the flat spot contacts and ceasescontact with the drum, along a line passing through the axle and throughthe point of contact between the drum and the tire. This acceleration ofthe axle is measured after one-half minute and after 5 minutes ofrotation at a rate corresponding to 30 miles per hour. This is the testthat was employed in example F.

Griege cord produced therefrom had a denier of 2.020 to 2,037. a l0poundelongation of 9.0 to 9.1 percent, an elongation at break of 22.7 to24.2, and a break load of 25.4 to 26.6 pounds. Tires were made using thegreige cord and were then subjected to the previously described tiretest. The axle acceleration after one-half minute was 3.7 g. and after 5minutes was 1.5 g.

The invention is illustrated on the accompanying drawing, wherein:

FIG. 1 is a sectional view of a pneumatic tire in accordance with thisinvention; and

FIG. 2 is a fragmentary perspective view of a tire cord in accordancewith this invention.

In the drawing, there is shown a four-ply pneumatic tire 10 havingembedded therein reinforcing cords 12 in accordance with this invention.An isolated cord 12 of the composition disclosed herein is shown in FIG.2 as comprising a plurality of individual filaments 14 piled and twistedtogether to form the cord 12.

iclaim:

l. A process for the treatment of polycarbonamide structures of theclass consisting of tire cords and filaments, which process comprisestreating said polycarbonamide structure,

seconds, and subsequently removing the treating agent from the surfaceof the structure and then heating the structure in an air oven at atemperature of l60l80 C. and thereby producing a structure having aninitial modulus and response lag which are substantially less than thoseof the structure before said treatment.

90mm UNITED S'iA'iICS PATENT OFFICE QERTIFICATE or CORRECTEON Patent No.3 ,621 ,090 Dated November 16, 19?].

lnventofls) Richard W. Kibler It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

C010 3, line 11, delete entire line 0015. 5-6, Table A, -A-2, "8.92"shouid read --8.93--

11-12, "untreated" should read ---unreacted-- sci.) 7, Table B, 3-1,"10.3" should read --19.3--

C011. 8 line 31, "change" should read --charge-- Cole. 7-8, Table D,13-2, "17.9" should read "27.9--

Cole. 9-10, Table D, footnote "N OH" should read --Na0H-- Col. 9, line67 "caused" should read --causes-- Signed and sealed this 23rd day ofMay 1972.

(SEAL) Actest:

EDWARD I LFLETCWR, JR. ROBERT GOTI'SCHALK attesting Officer Commissionerof Patents

